Synthetic detergent cake and process



United States Patent 3,057,805 SYNTHETIC DETERGENT CAKE AND PROCESS FOR MAKING THE SAME George G. Wittwer, 175 Astor Ave., Hawthorne, N.Y. No Drawing. Filed July 9, 1959, Ser. No. 825,881

4 Claims. (Cl. 252-161) This invention relates to a detergent composition, more specifically to a combination which not only exhibits a synergistic detergent effect, but also is of such character as to permit the manufacture of the composition in bar form. This application is a continuation in part of co pending application Serial No. 603,229, filed August 10, 1956, which is a continuation in part of application Serial No. 369,505, filed July 21, 1953, which in turn is a continuation in part of application Serial No. 221,746, filed April 18, 1951, now all abandoned.

In the past, common soaps consisting primarily of the alkali metal salts of the long chain fatty acids (principally sodium stearate and laurate) have been manufactured in bar form. However, while these soaps perform satisfactorily in soft water, their efiiciency in hard water is poor.

It is well known in the art that certain so-called synthetic detergents possess superior cleaning and wetting properties to those of ordinary household soaps, principally in that they are largely unaffected by the presence of hardness in the water, and they do not leave an undesirable scum on the surface of the water or on the sink or bathtub.

However, these detergents are of such a high degree of water solubility that if a detergent cake or bar is moistened, it becomes slimy and does not retain its shape. This makes it unsuitable for ordinary household use.

It is, therefore, among the objects of this invention to provide a detergent composition which can be produced in a bar form which will stand up under the usual conditions of use.

It is also among the objects of this invention to provide a detergent composition in bar form which contains no undesirable binding agents.

It is further among the objects of this invention to provide a composition capable of manufacture in bar form which exhibits a synergistic detergent effect.

To carry out the aforementioned objectives, there is provided a combination of an alkylaryl synthetic detergen and the stearic acid ester of sodium hydroxy isethionate. This composition not only serves to retain and maintain its cake or bar form, but also contributes synergistically to the overall detergent action. Thus, the effective detergency of the alkylaryl-isethionic mixture is greater than the detergencies of each compound alone.

The sodium stearoyl isethionate is commercially marketed under the trademark Drucal S and may be prepared by a straight-forward esterification of the sodium salt of isethionic acid by stearic acid. A more specific process is described in Reissue Patent No. 23,823 (Molteni et a1.) granted May 4, 1954.

The alkylaryl synthetic detergent may be any one or more of a rather wide variety of compounds. This class is exemplified by the formula- RRSO Na wherein R is an alkyl radical or group of alkyl radicals which average at least carbon atoms each and R is an aryl radical which may be modified by short chain alkyl radicals. The average of the alkyl radicals comprising R is preferably 12 to 18 carbon atoms in the absence of modifying groups (such as isoalkyls, alkylated toluenes, or poly alkyl benzenes) and solubilizing substituent groups (such as OH, COOH and NH on the aryl radi- 2 cal. If modifying or solubilizing groups are present, the alkyl radical may contain in excess of 20 carbon atoms.

Generally speaking, suitable alkylaryl detergents are those referred to in Synthetic Detergents, J. S. Mc- Cutcheon, New York, 1950 at page 120 et seq., which reference is incorporated herein.

In order to have satisfactory properties, the detergent in the bar should have from 10 to 90% alkylaryl synthetic detergent and from 90 to 10% of the isethtionic synthetic detergent on a dry weight basis. Obviously, .any of the well known fillers, diluents, extenders, antiseptics, perfumes and the like may be added to a bar made in accordance with the present invention without destroying the novel characteristics thereof. If any additives are present, the proportion of combined detergent and binder should be at least 20% by weight.

In preparing detergent bars according to this invention, a mixture of sodium alkylaryl detergent and sodium stearoyl isethionate in the solid state is subjected to a roller mixing operation. The resulting mixture is placed in a rotary blade mixer provided with means for heating, and Water in an amount of 15-20% of the charge of the mixer is added and the temperature during mixing maintained at 100 C. This operation is continued until a homogeneous mass is formed, and some water is evaporated, preferably to about 5%.

It is believed that some sort of fusion of the relatively insoluble sodium stearoyl isethionate with the alkyl aryl detergent takes place. Surprisingly enough, this results in a detergent bar in which there is no selective solubility.

After mixing and evaporation of water have progressed to the desired point, the mass is removed from the mixer for subsequent formation into any desired shape by the usual well known methods.

In the following specific examples, all parts are by weight on a dry basis. There is also present approximately 5% of the residual moisture as indicated in the foregoing description of the method of making a bar according to this invention.

Table of Compositions I Example No 1 2 3 4 5 6 Na. stearoyl isethi0nate Na Lauroyl isethionate.--" Na dodeeyl benzene sulfonate Na decyl benzene sulfonate. Na keryl benzene sultonata Corn Starch Tetra-Na-Pyro-phosphate- Aluminum sulfate Total Dry Weight Parts Table of Compositions II Example No 7 8 9 Na stearoyl isethionate Na Lauroyl isethionate Na dodecyl benzene sulionat Na lauryl sulfate. Corn Starch Tetra-Na-pyro-phosphate. Aluminum sulfate Total Dry Weight, Parts Table of Compositions III Example No 12 13 14 16 Na stearoyl isethionate Na dodecyl benzene sulfonate Total Dry Weight, Parts.

n O 7 Table of Compositions IV Example No 18 19 20 21 Na stearoyl isethionate- 27 Na Lauroyl isethionate- 27 Na dodecyl benzene sulfonate-.. 6

Total Dry Weight, Parts 60 60 6O 60 The foregoing examples are intended to be illustrative of the scope of this invention which is to be broadly construed and not to be limited except by the character of the claims appended hereto.

What is claimed is:

1. A solid detergent bar consisting essentially of a homogeneous mixture of from 10 to 90% of sodium stearoyl isethionate and from 90 to 10% of an alkylaryl sulfonate having detergent properties, the alkyl radicals of said sulfonate averaging at least 10 carbon atoms.

2. A solid detergent bar according to claim 1 wherein said isethionate and said sulfonate together comprise at least 20% by dry weight of said bar.

3. A solid detergent bar according to claim 1 wherein said sulfonate is taken from the class consisting of dodecyl benzene sodium sulfonate, decyl benzene sodium sulfonate, and keryl benzene sodium sulfonate.

4. The method of makinga solid detergent cake which comprises mixing sodium stearoyl isethionate with an alkylaryl sulfonate detergent having an average alkyl radical length of at least 10 carbon atoms, in such amounts as to produce a mixture consisting essentially of 10 to 90% of said detergent by dry weight and 90 to 10% of said isethionate by dry weight, adding 15 to 20% by weight of water, heating the slurry thus produced to 80-100" 0, agitating said slurry until a homogeneous fused mixture is achieved, continuing the heating of said mixture until the Water content has been reduced to not more than about 5% and forming the resultant fused mixture into bars.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,823 Molteni et al May 4, 1954 1,906,484 Nuesslein May 2, 1933 2,156,996 Martin May 2, 1939 2,175,285 Duncan Oct. 10, 1939 2,477,383 Lewis July 26, 1949 2,678,921 Turck May 18, 1954 

1. A SOLID DETERGENT BAR CONSISTING ESSENTIALLY OF A HOMOGENEOUS MIXTURE OF FROM 10 TO 90% OF SODIUM STEAROYL ISETHIONATE AND FROM 90 TO 10% OF AN ALKYLARYL SULFONATE HAVING DETERGENT PROPERTIES, THE ALKYL RADICALS OF SAID SULFONATE AVERAGING AT LEAST 10 CARBON ATOMS. 